I have them, and I do like them! It took eight weeks for the moco to get the "Custom Painted" lowers (Oh, and did I say I believe extremely way over priced) to rural Nevada. So, I got a lot of riding in with the wonderful stock headpipe. Memories fade, but I really don't believe there was much difference between dressed and undressed with regard to heat.
But, this is my first (and, will hopefully be my last) Harley. I've basically retired my 30 year old R100RT that has 100K on it. I haven't ridden her once since. She was the first of the full fairing Boxers and to me it just seemed right to have lowers on the SSERG. I complain about the SSERG heat. But, it's really nothing. If you want to really experience heat, stand on the footpegs with your feet tucked under the jugs on blistering hot asphalt. However, those jugs did work well in the winter.
And, one of my concerns is foot stability. I was used to the footpegs or really foot anchors. Those first two months, my feet were all over the place in wind and vibration. Honestly, the first time I took it up to the cubic inches, I backed off because my feet were moving on the floorboards (honestly, I never exceeded the breakin RPMs). The bike was stable as a rock, but my feet were trying to keep up. I don't dance well on the scoot. Lower fairings cured it. Now, my feet stay put.